The Supreme Court ruled yesterday that the government may force television and radio broadcasters to air the campaign ads of candidates for federal office.

Upholding a "new right of access" to television, the court said the Federal Communications Commission had the power to order the sale of 30 minutes of prime time to Jimmy Carter 11 months before the 1980 election. The networks had refused on the grounds that the campaign hadn't begun and that the ads would disrupt normal programming.

The ruling takes the FCC deeper than it's been into regulation of political broadcast content. A broadcaster can still deny air time to a candidate if the ads would "substantially" disrupt programming. But the candidate can then appeal to the FCC, which can order the ad run under penalty of license revocation.

Before, the FCC enforced only a generalized obligation to cover public issues and to allow equal time to candidates if a station allowed any time at all.

The networks argued that this new power upsets a delicate regulatory balance, cutting more deeply than ever into their constitutionally protected right to make editorial decisions and allowing the FCC to decide when campaigns begin.

By a 6-to-3 vote, the court said the networks' rights are outweighed by another protected right: "The ability of candidates to present, and the public to receive, information necessary for the effective operation of the democratic process."

Justice Byron R. White, joined by William H. Rehnquist and John Paul Stevens, said in dissent that the new authority is a "major departure" from the past that makes "substantial in roads" into journalistic freedom.

Reacting to the decision, NBC said yesterday that it "regrets that once again broadcasting is denied the rights and protections granted to print." The Media Action Project, an organization advocating increased access, called the ruling "an overdue reminder that service comes first and ratings second."

Carter requested the time for a December, 1979, announcement of his candidacy, and was rejected by all three of the major networks.

The Carter-Mondale campaign committee complained to the FCC, which said the networks had violated the Federal Election Campaign Act of 1971. The law allows license revocation for "willful or repeated failure to allow reasonable access to or to permit purchase of reasonable amounts of time" by a legally qualified candidate.

In the Court of Appeals for the District of Columbia, the networks contended that the provision created only a generalized obligation, like the obligation to air "public interest" programming, not a grant of power to the FCC to interfere with specific decisions involving specific candidates. That, they said, would violate their First Amendment rights.

Chief Justice Warren E. Burger, writing for the court, upheld the lower court's rejection of the network's arguments.

Burger said Congress meant to create "a right of access that enlarged the political broadcasting responsibilities of licensees."

The networks must consider requests on an "individualized basis" and "tailor their responses to accommodate, as much as reasonably possible, a candidate's stated purposes in seeking air time," he wrote.

But the right is not unlimited, he said. Broadcasters don't have to carry every requested advertisement. "To justify a negative response, broadcasters must cite a realistic danger of substantial program disruption . . . or of an excessive number of equal time requests," he said.The response must be in writing "to facilitate review" by the FCC.

"If broadcasters have considered the relevant factors in good faith, the commission will uphold their decisions," he said.

In addition, no time must be sold before a campaign begins. Contrary to the networks' claims, Burger said, the ruling does not leave that judgement to the FCC. Rather, the "electoral process" makes that judgment and the FCC follows it.

"Such a decision is not, and cannot be, purely one of editorial judgment," he said.

"The First Smandment interests of candidates and voters, as well as broadcasters," are involved in this issue, Burger wrote. "We have recognized that 'it is of particular importance that candidates have the opportunity to make their views known so that the electorate may intelligently evaluate the candidates' personal qualities and their positions on vital public issues before choosing among them on election day.'"

The law in question "represents an effort by Congress to assure that an important resource, the airwaves, will be used in the public interest," Burger said.